API reference / @evolu/common / Type / SetType

Interface: SetType<ElementType>

Defined in: packages/common/src/Type.ts:2487

SetType extends Type with an additional element property for reflection.

Extends

• Type<"Set", ReadonlySet<InferType<ElementType>>, ReadonlySet<InferInput<ElementType>>, SetError<InferError<ElementType>>, ReadonlySet<InferParent<ElementType>>, SetError<InferParentError<ElementType>>>

Type Parameters

Type Parameter
ElementType extends AnyType

Properties

Property	Modifier	Type	Description	Inherited from	Defined in
[EvoluTypeSymbol]	readonly	true	-	Type.[EvoluTypeSymbol]	packages/common/src/Type.ts:353
~standard	readonly	Props<ReadonlySet<InferInput<ElementType>>, ReadonlySet<InferType<ElementType>>>	The Standard Schema properties.	Type.~standard	packages/common/src/Type.ts:4450
element	readonly	ElementType	-	-	packages/common/src/Type.ts:2495
Error	public	SetError<InferError<ElementType>>	The specific error introduced by this Type. ### Example type StringError = typeof String.Error;	Type.Error	packages/common/src/Type.ts:221
Errors	readonly	| SetError<InferError<ElementType>> | SetError<InferParentError<ElementType>>	### Example type StringParentErrors = typeof String.Errors;	Type.Errors	packages/common/src/Type.ts:417
from	readonly	(value) => Result<ReadonlySet<InferType<ElementType>>, | SetError<InferError<ElementType>> | SetError<InferParentError<ElementType>>>	Creates T from an Input value. This is useful when we have a typed value. from is a typed alias of fromUnknown.	Type.from	packages/common/src/Type.ts:236
fromParent	readonly	(value) => Result<ReadonlySet<InferType<ElementType>>, SetError<InferError<ElementType>>>	Creates T from Parent type. This function skips parent Types validations when we have already partially validated value.	Type.fromParent	packages/common/src/Type.ts:330
fromUnknown	readonly	(value) => Result<ReadonlySet<InferType<ElementType>>, | SetError<InferError<ElementType>> | SetError<InferParentError<ElementType>>>	Creates T from an unknown value. This is useful when a value is unknown.	Type.fromUnknown	packages/common/src/Type.ts:322
Input	public	ReadonlySet<InferInput<ElementType>>	The type expected by from and fromUnknown. ### Example type StringInput = typeof String.Input;	Type.Input	packages/common/src/Type.ts:219
is	readonly	Refinement<unknown, ReadonlySet<InferType<ElementType>>>	A type guard that checks whether an unknown value satisfies the Type. ### Example const value: unknown = "hello"; if (String.is(value)) { // TypeScript now knows valueis astring here. console.log("This is a valid string!"); } const strings: unknown[] = [1, "hello", true, "world"]; const filteredStrings = strings.filter(String.is); console.log(filteredStrings); // ["hello", "world"]	Type.is	packages/common/src/Type.ts:351
name	readonly	"Set"	-	Type.name	packages/common/src/Type.ts:227
orNull	readonly	(value) => | ReadonlySet<InferType<ElementType>> | null	Creates T from an Input value, returning null if validation fails. This is a convenience method that combines from with getOrNull. When to use: - When you need to convert a validation result to a nullable value - When the error is not important and you just want the value or nothing ### Example // ✅ Good: Optional user input const age = PositiveInt.orNull(userInput); if (age != null) { console.log("Valid age:", age); } // ✅ Good: Default fallback const maxRetries = PositiveInt.orNull(config.retries) ?? 3; // ❌ Avoid: When you need to know why validation failed (use from instead) const result = PositiveInt.from(userInput); if (!result.ok) { console.error(formatPositiveError(result.error)); }	Type.orNull	packages/common/src/Type.ts:315
orThrow	readonly	(value) => ReadonlySet	Creates T from an Input value, throwing an error if validation fails. Throws an Error with the Type validation error in its cause property, making it debuggable while avoiding the need for custom error messages. This is a convenience method that combines from with getOrThrow. When to use: - Configuration values that are guaranteed to be valid (e.g., hardcoded constants) - Application startup where failure should crash the program - As an alternative to assertions when the Type error in the thrown Error's cause provides sufficient debugging information - Test code with known valid inputs (when error message clarity is not critical; for better test error messages, use Vitest schemaMatching + assert with .is()) ### Example // ✅ Good: Known valid constant const maxRetries = PositiveInt.orThrow(3); // ✅ Good: App configuration that should crash on invalid values const appName = SimpleName.orThrow("MyApp"); // ✅ Good: Instead of assert when Type error is clear enough // Context makes it obvious: count increments from non-negative value const currentCount = counts.get(id) ?? 0; const newCount = PositiveInt.orThrow(currentCount + 1); // ✅ Good: Test setup with known valid values const testUser = User.orThrow({ name: "Alice", age: 30 }); // ❌ Avoid: User input (use from instead) const userAge = PositiveInt.orThrow(userInput); // Could crash! // ✅ Better: Handle user input gracefully const ageResult = PositiveInt.from(userInput); if (!ageResult.ok) { // Handle validation error }	Type.orThrow	packages/common/src/Type.ts:284
Parent	public	ReadonlySet<InferParent<ElementType>>	The parent type. ### Example type StringParent = typeof String.Parent;	Type.Parent	packages/common/src/Type.ts:223
ParentError	public	SetError<InferParentError<ElementType>>	The parent's error. ### Example type StringParentError = typeof String.ParentError;	Type.ParentError	packages/common/src/Type.ts:225
Type	readonly	ReadonlySet	The type this Type resolves to. ### Example type String = typeof String.Type;	Type.Type	packages/common/src/Type.ts:364